Method for determining the stress of steel bars in axial tension members and reinforcement method for axial tension members

Abstract

The present application provides a method for determining the stress of steel bars in an axial tension member and a method for arranging the reinforcement of the axial tension member, the method comprising the following steps: obtaining the axial force borne by the axial tension member; obtaining the axial tensile strength of ultra-high performance concrete; determining the cross-sectional area of ​​the tensioned steel bars and the effective reinforcement ratio of the tensioned steel bars according to the axial force borne by the axial tension member and the axial tensile strength of ultra-high performance concrete; determining the stress of the tensioned steel bars according to the axial force borne by the axial tension member, the cross-sectional area of ​​the tensioned steel bars, the effective reinforcement ratio of the tensioned steel bars and the axial tensile strength of ultra-high performance concrete. The tensile effect of ultra-high performance concrete is fully considered, and the applicability range is wider and the reliability is higher. Compared with the traditional calculation method, the predicted results are more consistent with the measured results, which can fully reflect the influence of the characteristics of ultra-high performance concrete on the stress of steel bars, is easy to use in engineering practice, and can provide a reference for the structural design of ultra-high performance concrete axial tension members, which has important engineering application value.

Description

Technical Field

[0001] One or more embodiments of the present specification relate to the technical field of bridge design, and in particular, to a method for determining the stress of steel bars in an axial tension member and a method for arranging reinforcement for the axial tension member. Background Art

[0002] Ultra high performance concrete (UHPC) is a cement-based composite material with ultra-high mechanical properties and ultra-long durability. Experience has shown that the use of UHPC structures can effectively reduce material consumption and carbon emissions, significantly improve the structure's crack resistance, and extend the service life of the structure. UHPC materials have not yet been widely used in domestic bridge projects. The main reason is the lack of relevant UHPC structural design specifications in the domestic highway bridge industry. Among them, crack width verification is one of the important contents in the bridge structure design specifications. Among them, steel bar stress is the most important factor affecting the size of the crack width of concrete components. Therefore, the reasonable calculation of the steel bar stress in the cracked section is an important prerequisite for predicting the crack width of reinforced concrete components.

[0003] At present, the design specifications for ordinary concrete structures, "Concrete Structure Design Code" (GB 50010-2010) and "Highway Bridge and Culvert Reinforced Concrete and Prestressed Concrete Bridge and Culvert Design Code" (JTG 3362-2018), use σ2 for the stress of the cracked section of the steel bars of ordinary reinforced concrete axial tension members. ss =N / A s Calculation cannot reflect the effect of the tensile properties of ultra-high performance concrete on the stress of steel bars, resulting in a deviation between the stress calculation of the steel bars and the actual stress conditions, making it difficult to meet the design requirements. Summary of the invention

[0004] In view of this, the purpose of one or more embodiments of the present specification is to propose a method for determining the stress of steel bars in an axial tension member and a reinforcement method for an axial tension member, which has a wide range of applicability and high reliability.

[0005] In a first aspect, a method for determining the stress of steel bars of an axial tension member is provided, and the method for determining the stress of steel bars of an axial tension member comprises the following steps:

[0006] Obtain the axial force borne by the axial tension member;

[0007] Obtaining the axial tensile strength of ultra-high performance concrete;

[0008] According to the axial force borne by the axial tension member and the axial tensile strength of the ultra-high performance concrete, the cross-sectional area of ​​the tensile steel bars and the effective reinforcement ratio of the tensile steel bars are determined;

[0009] The stress of the tensioned steel bar is determined according to the axial force borne by the axial tension member, the cross-sectional area of ​​the tensioned steel bar, the effective reinforcement ratio of the tensioned steel bar and the axial tensile strength of the ultra-high performance concrete.

[0010] In the above technical scheme, the tensile effect of ultra-high performance concrete is fully considered, and the applicability is wider and the reliability is higher. Compared with the traditional calculation method, the predicted results are more consistent with the measured results, which can fully reflect the influence of ultra-high performance concrete characteristics on steel stress. It is easy to use in engineering practice and can provide a reference for the structural design of ultra-high performance concrete axial tension components, which has important engineering application value.

[0011] In a specific possible implementation scheme, the stress of the tensile steel bar is determined according to the axial force borne by the axial tension member, the cross-sectional area of ​​the tensile steel bar, the effective reinforcement ratio of the tensile steel bar and the axial tensile strength of the ultra-high performance concrete, specifically:

[0012] The stress of the tensioned steel bar is determined according to the axial force balance condition, the axial force borne by the obtained axial tension member, the cross-sectional area of ​​the tensioned steel bar, the effective reinforcement ratio of the tensioned steel bar and the axial tensile strength of the ultra-high performance concrete.

[0013] In a specific embodiment, the stress of the tensile steel bar satisfies the following formula:

[0014]

[0015] Among them, σ ss is the stress of the tensile reinforcement; N is the axial force borne by the axial tension member; A s is the cross-sectional area of ​​the tensile reinforcement, f t is the axial tensile strength of ultra-high performance concrete; ρ s is the effective reinforcement ratio of the tensile reinforcement.

[0016] In a specific possible implementation manner, the axial tension member is an axial tension member used in an ultra-high performance concrete bridge.

[0017] In a specific possible implementation scheme, the axial force borne by the axial tension member is obtained as follows:

[0018] The axial force borne by the axial tension member is determined by obtaining the internal force borne by the bridge.

[0019] In a second aspect, a method for predicting crack width of a reinforced concrete member is provided, the method comprising the following steps:

[0020] Determine the stress of the tensile steel bars of the axial tension member by using any of the above determination methods;

[0021] The crack width of reinforced concrete components is predicted based on the determined stress of the tensile reinforcement.

[0022] In the above technical scheme, the tensile effect of ultra-high performance concrete is fully considered, and the applicability is wider and the reliability is higher. Compared with the traditional calculation method, the predicted results are more consistent with the measured results, which can fully reflect the influence of ultra-high performance concrete characteristics on steel stress. It is easy to use in engineering practice and can provide a reference for the structural design of ultra-high performance concrete axial tension components, which has important engineering application value.

[0023] In a specific possible implementation method, the prediction of the crack width of the reinforced concrete member according to the determined stress of the tensile steel bar is specifically as follows:

[0024]

[0025] Among them, w smax is the crack width prediction of reinforced concrete components; ψ is the strain non-uniformity coefficient of the longitudinal tensile reinforcement between cracks; σ ss is the tensile reinforcement stress; E s is the elastic modulus of the tensile reinforcement; l cr is the average crack spacing.

[0026] In a specific possible implementation scheme, the longitudinal tensile reinforcement strain non-uniformity coefficient ψ between the cracks is;

[0027]

[0028] Among them, K global is the overall fiber orientation coefficient, which is taken as 1.25.

[0029] In a specific embodiment, the average crack spacing l cr for:

[0030]

[0031] Among them, c s is the thickness of the steel bar protective layer; d eq is the elastic modulus of the tensile reinforcement.

[0032] In a third aspect, a reinforcement method for an axial tension member is provided, the method comprising the following steps:

[0033] Determine the stress of the tensile steel bars of the axial tension member by using any of the above determination methods;

[0034] According to any of the above methods for predicting crack width of reinforced concrete components, the crack width of the axial tension component is determined; the crack width of the determined axial tension component is compared with a set crack width; if the crack width exceeds the set crack width, the cross-sectional area of ​​the tensioned steel bars and the effective reinforcement ratio of the tensioned steel bars are adjusted.

[0035] In the above technical scheme, the tensile effect of ultra-high performance concrete is fully considered, and the applicability is wider and the reliability is higher. Compared with the traditional calculation method, the predicted results are more consistent with the measured results, which can fully reflect the influence of ultra-high performance concrete characteristics on steel stress. It is easy to use in engineering practice and can provide a reference for the structural design of ultra-high performance concrete axial tension components, which has important engineering application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate one or more embodiments of the present specification or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only one or more embodiments of the present specification. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0037] Figure 1 A flow chart of a method for determining the stress of steel bars of an axial tension member provided in an embodiment of the present application;

[0038] Figure 2 A schematic diagram of the structure of the test piece provided in the embodiment of the present application;

[0039] Figure 3a to Figure 3b A schematic diagram of the internal structure of a test piece provided in an embodiment of the present application;

[0040] Figure 4a to Figure 4e A schematic diagram comparing the measured and calculated stress values ​​of the steel bars provided in the embodiment of the present application;

[0041] Figure 5 A schematic diagram comparing the steel bar stress calculation provided by the embodiment of the present application with the steel bar stress calculation by the existing method provided by the embodiment of the present application;

[0042] Figure 6 A method for predicting crack width of reinforced concrete components provided in an embodiment of the present application;

[0043] Figure 7a to Figure 7e A schematic diagram comparing the crack width prediction value and the experimental value provided for this application;

[0044] Figure 8 A flow chart of a reinforcement method for an axially tensioned member provided in an embodiment of the present application. DETAILED DESCRIPTION

[0045] In order to make the objectives, technical solutions and advantages of the present disclosure more clearly understood, the present disclosure is further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.

[0046] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in one or more embodiments of this specification should be understood by people with ordinary skills in the field to which this disclosure belongs. The "first", "second" and similar words used in one or more embodiments of this specification do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0047] To facilitate understanding of the method for determining the stress of steel bars in an axial tension member provided in the embodiment of the present application, its application scenario is first explained. The method for determining the stress of steel bars in an axial tension member provided in the embodiment of the present application is used to determine the stress of steel bars in the bridge design process, thereby improving the safety and durability of bridge design. At present, the calculation of steel bar stress is based on the cross-sectional area of ​​the tensile steel bar and the axial force borne by the axial tension member, and the calculation ignores the effect of concrete tensile strength. However, for ultra-high performance concrete, a large amount of steel fibers are incorporated into its matrix, showing excellent tensile toughness. After the ultra-high performance concrete matrix cracks, the randomly distributed steel fibers can effectively bridge the micro-cracks of the ultra-high performance concrete and continue to bear the tensile force, thereby effectively sharing the tensile force of the steel bars at the cracks. Therefore, it is necessary to establish a method for calculating the stress of steel bars in the cracked section of an axial tension member that reasonably considers the tensile effect of ultra-high performance concrete. The following is a detailed description of it in conjunction with specific drawings and embodiments.

[0048] Due to the excellent post-crack tensile strength of ultra-high performance concrete and its good bonding properties with steel bars, the stress of cracked cross-section steel bars in ultra-high performance concrete axial tension components can be effectively reduced. However, the existing technology does not fully reflect the influence of ultra-high performance concrete characteristics on steel bar stress. To this end, the embodiment of the present invention introduces an ultra-high performance concrete tensile strength influence item on the basis of the traditional calculation method to reflect the influence of ultra-high performance concrete characteristics on steel bar stress, ensure that the formula prediction value is more in line with the actual situation, and ultimately make the method have the characteristics of wider application range and higher reliability. It should be emphasized that the ultra-high performance concrete tensile strength influence item in the embodiment of the present invention is not selected at random.

[0049] First of all, it should be noted that the method for determining the stress of the steel bars of the axial tension member provided in the embodiment of the present application needs to meet certain conditions:

[0050] Combined with the mechanical characteristics of UHPC, the basic assumptions for calculating the stress of steel bars in the cracked section of reinforced UHPC axial tension members include:

[0051] (1) Ignore the slip between UHPC and steel bars; that is, ignore the slip between UHPC and steel bars when the axial tension member cracks.

[0052] (2) Considering the tensile effect of UHPC in the tensile zone, that is, the axial tensile strength of ultra-high performance concrete, considering the material properties of UHPC itself, due to the large amount of steel fibers added to its matrix, it exhibits excellent tensile toughness. Therefore, after the ultra-high performance concrete matrix cracks, the randomly distributed steel fibers can effectively bridge the micro-cracks of the ultra-high performance concrete and continue to bear the tensile force, thereby effectively sharing the tensile force of the steel bars at the cracks.

[0053] (3) The tensile steel bars are in the normal use stage, that is, the tensile steel bars have not reached the yield strength of the steel bars, and their stress and strain are in a linear relationship.

[0054] refer to Figure 1 Based on the above basic assumptions, the method for determining the stress of the steel bars of the axial tension member provided in the embodiment of the present application includes the following steps:

[0055] Step 001: Obtain the axial force borne by the axial tension component;

[0056] Specifically, the axial force borne by the axial tension member is determined by obtaining the bearing capacity of the bridge. The axial force borne by the axial tension member is determined based on the bearing load during bridge design, as well as the number and location of the axial tension member. Through mechanical analysis, the axial force borne by the axial tension member can be determined based on the external load during bridge design, as well as the number and location of the axial tension member. The above-mentioned specific mechanical analysis is a conventional basic mechanical analysis, and therefore will not be described in detail in the embodiments of this application.

[0057] Step 002: Obtaining the axial tensile strength of ultra-high performance concrete;

[0058] Specifically, the axial tensile strength of ultra-high performance concrete can be obtained through its material properties. Alternatively, it can be obtained through experiments. The specific experimental method is a conventional tensile test, which will not be described in detail here.

[0059] Step 003: Determine the cross-sectional area of ​​the tension steel bars and the effective reinforcement ratio of the tension steel bars according to the obtained axial force borne by the axial tension member and the axial tensile strength of the ultra-high performance concrete;

[0060] Specifically, the axial force borne by the axial tension member is mainly borne by the tension steel bars, but ultra-high performance concrete will also be involved. For this reason, when setting the tension steel bars, the axial force borne by the axial tension member and the axial tensile strength of the ultra-high performance concrete can be fully considered to determine the cross-sectional area of ​​the tension steel bars and the effective reinforcement ratio of the tension steel bars. Among them, the cross-sectional area of ​​the tension steel bars refers to the sum of the cross-sectional areas of all steel bars, that is, the cross-sectional area of ​​a single steel bar * the total number of steel bars. The effective reinforcement ratio is the total amount of steel bars in the axial tension member, specifically: As / Ac, where As is the cross-sectional area of ​​the tension steel bars, and Ac is the cross-sectional area of ​​the ultra-high performance concrete.

[0061] Step 004: Determine the stress of the tensile steel bars according to the axial force borne by the axial tension member, the cross-sectional area of ​​the tensile steel bars, the effective reinforcement ratio of the tensile steel bars, and the axial tensile strength of the ultra-high performance concrete.

[0062] Specifically, when the above data is used to obtain the stress of the tensile steel bar, the stress of the tensile steel bar is determined based on the axial force balance condition, the cross-sectional area of ​​the tensile steel bar, the effective reinforcement ratio of the tensile steel bar, and the axial tensile strength of the ultra-high performance concrete. It specifically satisfies the following formula:

[0063] According to the axial force balance condition, the formula is established

[0064] N = f t A c +σ ss A s (1)

[0065] In the formula: σ ss is the stress of the tensile reinforcement; N is the axial force borne by the axial tension member; As is the cross-sectional area of ​​the tensile reinforcement, f t is the axial tensile strength of ultra-high performance concrete; Ac is the cross-sectional area of ​​ultra-high performance concrete.

[0066] From formula (1), we can get the tensile stress of the steel bar in the cracked section:

[0067]

[0068] Where: ss is the stress of the tensile reinforcement; N is the axial force borne by the axial tension member; As is the cross-sectional area of ​​the tensile reinforcement, f t is the axial tensile strength of ultra-high performance concrete; ρ s is the effective reinforcement ratio of the tensile reinforcement. s =As / Ac.

[0069] That is, the stress of the tensile reinforcement satisfies the following formula:

[0070] The above method fully considers the tensile effect of ultra-high performance concrete, has a wider range of applicability and higher reliability. Compared with the traditional calculation method, the predicted results are more consistent with the measured results, can fully reflect the influence of ultra-high performance concrete characteristics on steel stress, is easy to use in engineering practice, and can provide a reference for the structural design of ultra-high performance concrete axial tension components, which has important engineering application value.

[0071] To facilitate understanding of the above-mentioned calculation method of steel bar stress provided in the embodiment of the present application, an experimental verification is performed below.

[0072] like Figure 2 As shown, Figure 2 The structure of the test piece is shown in FIG. 1 . The present embodiment uses a dumbbell-shaped test piece with a test section size of 50×100 mm. The cross-sectional size of the end of the test piece is 100×100 mm. The size and reinforcement of the reinforced ultra-high performance concrete axial tension member are shown in FIG. Figure 3a and Figure 3b As shown. The steel bars are arranged symmetrically, and three HRB400 longitudinal steel bars ① are set in each specimen, with a center spacing of 30 mm; stirrups ② with a diameter of 8 mm are set at the ends to prevent the concrete from cracking prematurely at the ends during loading, and stand-off steel bars ③ are set to fix the spatial position of the steel bars. A total of 5 groups of reinforced ultra-high performance concrete axial tension members were designed, with 3 specimens in each group. The test parameters include reinforcement ratio, fiber orientation and fiber interface chemical treatment. The test parameters and specimen numbers are shown in Table 1.

[0073] Table 1 Specimen parameters

[0074]

[0075] The measured values ​​of the steel bar stress of the ultra-high performance concrete axial tension member are compared with the calculated values ​​based on formula (2). Figure 4a to Figure 4e As shown. It can be seen that in normal use, the calculated value of steel bar stress in formula (2) is generally consistent with the measured value, the mean of the ratio of the measured value to the calculated value is in the range of 1.00 to 1.33, and the standard deviation is in the range of 0.03 to 0.48. It can be seen that formula (2) considering the tensile effect of ultra-high performance concrete can better calculate the stress of the cracked section steel bar of reinforced ultra-high performance concrete axial tension components.

[0076] In order to better illustrate the advantages of the calculation method of the cracked section steel bar stress of the ultra-high performance concrete axial tension member of this embodiment, the existing calculation method is used to analyze the cracked section steel bar stress of some specimens in this embodiment. The existing calculation method formula is as follows

[0077]

[0078] Figure 5The steel bar stress of specimens AT-S10 and RT-S8 calculated by formula (3) is given and compared with the steel bar stress measured in the test. It can be found that the calculated steel bar stress value based on formula (3) is much larger than the measured steel bar stress value. This is because the calculation of the steel bar stress of the cracked section of the traditional reinforced concrete axial tension member does not take into account the tensile effect of concrete and overestimates the steel bar stress of the cracked section.

[0079] In summary, the steel bar stress determination method provided in the embodiment of the present application fully considers the tensile effect of ultra-high performance concrete, has a wider range of applicability and higher reliability. Compared with the traditional calculation method, the prediction results are more consistent with the measured results, can fully reflect the influence of ultra-high performance concrete characteristics on steel bar stress, is easy to use in engineering practice, can provide a reference for the structural design of ultra-high performance concrete axial tension components, and has important engineering application value.

[0080] refer to Figure 6 The present application also provides a method for predicting the crack width of a reinforced concrete member, the method comprising the following steps:

[0081] Step 001: Determine the stress of the tensile steel bars of the axial tension member by using any of the above determination methods;

[0082] Specifically, refer to Figure 1 The method for determining the steel bar stress of the axial tension member shown in will not be repeated in detail here.

[0083] Step 002: Predict the crack width of the reinforced concrete member based on the determined stress of the tensile reinforcement.

[0084] Specifically, the crack width is calculated according to the formula, which is as follows:

[0085]

[0086] Among them, w smax is the crack width prediction of reinforced concrete components; ψ is the strain non-uniformity coefficient of the longitudinal tensile reinforcement between cracks; σ ss is the stress of the tensile reinforcement; Es is the elastic modulus of the tensile reinforcement; l cr is the average crack spacing.

[0087] When determining the strain non-uniformity coefficient ψ of the longitudinal tensile reinforcement between cracks, the formula (5) can be used:

[0088]

[0089] Among them, K global is the overall fiber orientation coefficient, which is taken as 1.25.

[0090] In determining the average crack spacing l crWhen , the following formula (6) can be used:

[0091]

[0092] Among them, c s is the thickness of the steel bar protective layer; d eq is the elastic modulus of the tensile reinforcement.

[0093] The crack width of reinforced concrete components can be predicted by the above formulas (4), (5) and (6).

[0094] For reference Figure 7a to Figure 7e , Figure 7a to Figure 7e For Figure 4a to Figure 4e Comparison of the calculated predicted crack width of reinforced concrete structure with the experimental value corresponding to the stress of the tensile reinforcement in the example. Figure 7a to Figure 7e It can be seen that the crack width predicted by this method is not much different from the crack width measured in the experiment. Therefore, the crack width prediction method disclosed in this application can provide a more accurate calculation method and improve the safety design effect of the bridge.

[0095] From the above description, it can be seen that the tensile effect of ultra-high performance concrete is fully considered, and the applicability range is wider and the reliability is higher. Compared with the traditional calculation method, the predicted results are more consistent with the measured results, which can fully reflect the influence of ultra-high performance concrete characteristics on steel stress. It is easy to use in engineering practice and can provide a reference for the structural design of ultra-high performance concrete axial tension components, which has important engineering application value.

[0096] refer to Figure 8 The embodiment of the present application also provides a reinforcement method for an axial tension member, the method comprising the following steps:

[0097] Step 001: Determine the stress of the tensile steel bars of the axial tension member by using any of the above determination methods;

[0098] For details, please refer to Figure 1 Related description in .

[0099] Step 002: Determine the crack width of the axial tension member according to any of the above methods for predicting the crack width of a reinforced concrete member;

[0100] Specifically, refer to Figure 6 The relevant description in will not be repeated here.

[0101] Step 003: Compare the determined crack width of the axial tension member with the set crack width; if the crack width exceeds the set crack width, adjust the cross-sectional area of ​​the tensioned steel bar and the effective reinforcement ratio of the tensioned steel bar.

[0102] Specifically, when designing an axial tension member, there are certain requirements for the strength of the tensioned steel bars. When the tensioned steel bars cannot meet the requirements, the tensioned steel bars need to be redesigned. Therefore, in the embodiment of the present application, the crack width of the axial tension member determined is compared with the set crack width; if the crack width exceeds the set crack width, the cross-sectional area of ​​the tensioned steel bars and the effective reinforcement ratio of the tensioned steel bars are adjusted, thereby ensuring the structural strength of the designed axial tension member.

[0103] In summary, the technical solution provided by this application fully considers the tensile effect of ultra-high performance concrete, has a wider range of applicability and higher reliability. Compared with traditional calculation methods, the predicted results are more consistent with the measured results, can fully reflect the influence of ultra-high performance concrete characteristics on steel stress, is easy to use in engineering practice, and can provide a reference for the structural design of ultra-high performance concrete axial tension components, which has important engineering application value.

[0104] Those skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of the present disclosure (including the claims) is limited to these examples. In line with the present disclosure, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of different aspects of one or more embodiments of the present specification as described above, which are not provided in detail for the sake of simplicity.

[0105] While the disclosure has been described in conjunction with specific embodiments thereof, many alternatives, modifications and variations of these embodiments will be apparent to those skilled in the art in light of the foregoing description.

[0106] One or more embodiments of this specification are intended to cover all such substitutions, modifications and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of one or more embodiments of this specification should be included in the scope of protection of this disclosure.

Claims

1. A method for determining the stress of steel bars in an axial tension member, characterized in that: The following steps are involved: Obtain the axial force borne by the axial tension member; Obtaining the axial tensile strength of ultra-high performance concrete; According to the axial force borne by the axial tension member and the axial tensile strength of the ultra-high performance concrete, the cross-sectional area of ​​the tensile steel bars and the effective reinforcement ratio of the tensile steel bars are determined; Determining the stress of the tensioned steel bar according to the axial force borne by the axial tension member, the cross-sectional area of ​​the tensioned steel bar, the effective reinforcement ratio of the tensioned steel bar, and the axial tensile strength of the ultra-high performance concrete; The stress of the tensioned steel bar is determined according to the axial force borne by the axial tension member, the cross-sectional area of ​​the tensioned steel bar, the effective reinforcement ratio of the tensioned steel bar and the axial tensile strength of the ultra-high performance concrete, specifically: Determine the stress of the tensioned steel bar according to the axial force balance condition, the axial force borne by the obtained axial tension member, the cross-sectional area of ​​the tensioned steel bar, the effective reinforcement ratio of the tensioned steel bar, and the axial tensile strength of the ultra-high performance concrete; The stress of the tensile steel bar satisfies the following formula: in, is the tensile reinforcement stress; N The axial force borne by the axial tension member; A s is the cross-sectional area of ​​the tensile reinforcement, is the axial tensile strength of ultra-high performance concrete; ρ s is the effective reinforcement ratio of the tensile reinforcement.

2. The method for determining the stress of steel bars of an axial tension member according to claim 1, characterized in that: The axial tension member refers to an axial tension member used in ultra-high performance concrete bridges.

3. The method for determining the stress of steel bars of an axial tension member according to claim 1, characterized in that: The method for obtaining the axial force borne by the axial tension member is specifically as follows: The axial force borne by the axial tension member is determined by obtaining the internal force borne by the bridge.

4. A method for predicting crack width of reinforced concrete member, characterized in that: The following steps are involved: Determine the stress of the tensile steel bars of the axial tension member by using the determination method of any one of claims 1 to 3; Predict the crack width of reinforced concrete components based on the determined stress of the tensile reinforcement; The method of predicting the crack width of the reinforced concrete member according to the determined stress of the tensile steel bar is as follows: Among them, w smax To predict crack width of reinforced concrete components; is the strain non-uniformity coefficient of the longitudinal tensile reinforcement between cracks; is the tensile reinforcement stress; E s is the elastic modulus of the tensile reinforcement; is the average crack spacing.

5. The method for predicting crack width of reinforced concrete member according to claim 4, characterized in that: The non-uniform strain coefficient of the longitudinal tensile reinforcement between the cracks for; in, is the overall fiber orientation coefficient and is taken as 1.

25.

6. The method for predicting crack width of reinforced concrete member according to claim 4, characterized in that: The average crack spacing for: Among them, c s is the thickness of the steel bar protective layer; d eq is the elastic modulus of the tensile reinforcement.

7. A reinforcement method for an axial tension member, characterized in that: The following steps are involved: Determine the stress of the tensile steel bars of the axial tension member by using the determination method of any one of claims 1 to 3; Determine the crack width of the axial tension member according to the method for predicting the crack width of a reinforced concrete member as claimed in any one of claims 4 to 6; compare the determined crack width of the axial tension member with the set crack width; If the crack width exceeds the set value, the cross-sectional area of ​​the tensile steel bars and the effective reinforcement ratio of the tensile steel bars are adjusted.

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